Page 961 - techequipmentscatalogue2016
P. 961
FL.UKE ®
To perform the test: • The key to a good switch
test is repeatability.
With a modem documenting calibrator you can test for dry contacts opening and Repeatability is best
closing on the switch or if you are using the Fluke 753 or 754 you can leave the achieved by applying a
switch connected to the live voltage and the calibrator will measure the changing slow change in pressure to
AC voltage and interpret it as opening and closing of the switch. the switch as it approaches
its set or reset pressure.
One cautionary note: it is always safer to test a de-energized circuit but this is not
always possible. Also, do not measure AC voltages above 300 V ac as that is the • When performing the test
maximum rating of the 75X family. 480 V ac 3-phase voltages must be de-energized find out where the switch
and disconnected from the switch if testing with the 75X family. sets and make sure the
vernier/fine adjustment of
To get started testing the switch, connect as shown above. In this example your test pump has enough
adjustment to vary the
1 we will test dry contacts and continuity. To measure continuity for the test pressure up to the set point.
select resistance measurement. Then toggle to the source screen mode In this way the pressure
and select pressure to display the pressure generated by the hand pump can be changed slowly
and measured by the pressure module. Advance the calibrator mode to the capturing an accurate
split screen test mode. switch set point pressure.
Repeat this procedure for
The next step is to describe the switch and whether it is normally open the reset point.
2 or closed at ambient pressure. The relaxed state of the switch is the • With practice you can get
the vernier of the pump
reset state. The set state is the condition of the switch it changes to with within range of the set and
applied pressure or vacuum. In this example the switch is normally open reset point pressure and
and is expected to close when the pressure applied exceeds 10 psi. Next get excellent repeatability
the allowable pressure variance of the switch set state and deadband size of your tests (within the
needs to be defined. In this example the ideal switch set value is limitations of the switch
10 psi and is allowed +/ - I psi of deviation. The allowable reset pressure being tested).
is described in the deadband tolerance. In this instance the reset state
must be more than I psi less than the found set pressure but not greater Additional resources
than 3 psi less than the found set pressure.
For more in depth information
Once the test tolerances are fully defined start the test. Increase the about this application check out
these videos and application notes
3 pressure until the calibrator captures the set state pressure value. Then from Fluke.
decrease the pressure until the reset pressure is found. Repeat increasing § ] Pressure switch video
and decreasing the pressure across the switch looking for repeatability in
your set and reset pressure measurements. Once satisfied with the result ~
press done to get the pass/fail evaluation of the switch. If the switch fails
the test adjustment or replacement of the switch may be required. If the r!!l Pressure switch
switch is adjusted repeat the test to document the As-Left condition of the
switch before putting back into service. The test result is now documented ~ application note
and ready for upload to calibration management software. Pressure calibration
application note
www.tech-equipments.comlsales@tech-equipments.com 955
To perform the test: • The key to a good switch
test is repeatability.
With a modem documenting calibrator you can test for dry contacts opening and Repeatability is best
closing on the switch or if you are using the Fluke 753 or 754 you can leave the achieved by applying a
switch connected to the live voltage and the calibrator will measure the changing slow change in pressure to
AC voltage and interpret it as opening and closing of the switch. the switch as it approaches
its set or reset pressure.
One cautionary note: it is always safer to test a de-energized circuit but this is not
always possible. Also, do not measure AC voltages above 300 V ac as that is the • When performing the test
maximum rating of the 75X family. 480 V ac 3-phase voltages must be de-energized find out where the switch
and disconnected from the switch if testing with the 75X family. sets and make sure the
vernier/fine adjustment of
To get started testing the switch, connect as shown above. In this example your test pump has enough
adjustment to vary the
1 we will test dry contacts and continuity. To measure continuity for the test pressure up to the set point.
select resistance measurement. Then toggle to the source screen mode In this way the pressure
and select pressure to display the pressure generated by the hand pump can be changed slowly
and measured by the pressure module. Advance the calibrator mode to the capturing an accurate
split screen test mode. switch set point pressure.
Repeat this procedure for
The next step is to describe the switch and whether it is normally open the reset point.
2 or closed at ambient pressure. The relaxed state of the switch is the • With practice you can get
the vernier of the pump
reset state. The set state is the condition of the switch it changes to with within range of the set and
applied pressure or vacuum. In this example the switch is normally open reset point pressure and
and is expected to close when the pressure applied exceeds 10 psi. Next get excellent repeatability
the allowable pressure variance of the switch set state and deadband size of your tests (within the
needs to be defined. In this example the ideal switch set value is limitations of the switch
10 psi and is allowed +/ - I psi of deviation. The allowable reset pressure being tested).
is described in the deadband tolerance. In this instance the reset state
must be more than I psi less than the found set pressure but not greater Additional resources
than 3 psi less than the found set pressure.
For more in depth information
Once the test tolerances are fully defined start the test. Increase the about this application check out
these videos and application notes
3 pressure until the calibrator captures the set state pressure value. Then from Fluke.
decrease the pressure until the reset pressure is found. Repeat increasing § ] Pressure switch video
and decreasing the pressure across the switch looking for repeatability in
your set and reset pressure measurements. Once satisfied with the result ~
press done to get the pass/fail evaluation of the switch. If the switch fails
the test adjustment or replacement of the switch may be required. If the r!!l Pressure switch
switch is adjusted repeat the test to document the As-Left condition of the
switch before putting back into service. The test result is now documented ~ application note
and ready for upload to calibration management software. Pressure calibration
application note
www.tech-equipments.comlsales@tech-equipments.com 955
